Specific strains of dogs, affected with well-characterized hereditary retinal degenerations (Irish setter: Rod-Cone Dysplasia, miniature poodle: Progressive Rod-Cone Degeneration, Norwegian elkhound: Early Retinal Degeneration, Alaskan malamute: Hemeralopial, together with appropriate nonaffected control dogs, will be bred and maintained. The progeny of these dogs will be distributed to approved research investigators, either directly or by collection, processing and distribution of requested tissues. The primary aims in breeding setters, poodles and elkhounds are to ensure the continued availability of their respective mutations and to promote their utilization by research investigators. The primary aim in breeding malamutes is to preserve this unique mutation and ensure its future availability. The utilization of these mutants will be promoted by solicitation of requests from investigators. Responses will be reviewed for scientific merit and prioritized by an independent Animal Distribution Committee (ADC). The allocation and distribution of dogs and/or tissues will be according to the priorities set by the ADC. Assistance will be offered to investigators in development and implementation of specific protocols for optimal utilization of these mutants.